Gaze calibration via motion detection for eye-mounted displays

Abstract

An eye-mounted display can be calibrated relative to a user's gaze. A calibration system causes the eye-mounted display to project a calibration image onto the user's retina. The system detects eye movement as the user looks towards the calibration image. Once the detected eye movement indicates that the user's gaze is centered gaze on the calibration image, the system determines a calibration parameter representative of the user's gaze or the detected eye movement. The calibration parameter can be, for example, a pixel offset relative to an initial image source location or an image source pixel corresponding to the user's centered gaze. Subsequent images are then projected by the eye-mounted display onto the user's retina based on the calibration parameter.

What is claimed is: 
     
       1. A method for calibrating an alignment of an eye-mounted display to a user's gaze, the eye-mounted display comprising an image source, the method implemented on a system and comprising:
 providing a visual stimulus to the user comprising projecting a calibration image from the image source onto the user's retina; 
 sensing a motion of the user's eye in reaction to the visual stimulus; and 
 calibrating an alignment of the image source to the user's gaze based on the sensed motion by:
 comparing the sensed motion to a threshold; and 
 based on the comparison:
 maintaining a location of a visual center of the image source when the sensed motion is below a threshold, wherein the visual center is a location on the image source estimated to project to a center of the user's fovea; and 
 adjusting the location of the visual center of the image source when the sensed motion is greater than the threshold. 
 
 
 
     
     
       2. The method of  claim 1 , where calibrating the alignment of the image source to the user's gaze is based on a direction of the sensed motion. 
     
     
       3. The method of  claim 1 , where calibrating the alignment of the image source to the user's gaze is based on a magnitude of the sensed motion. 
     
     
       4. The method of  claim 1 , where sensing the motion of the user's eye comprises sensing a rotation of the user's eye in the user's eye socket. 
     
     
       5. The method of  claim 1 , where providing the visual stimulus to the user comprises projecting the calibration image from the visual center of the image source onto the retina. 
     
     
       6. The method of  claim 1 , adjusting the location of the visual center of the image source comprises adjusting the visual center in a direction to compensate for a direction of the sensed motion. 
     
     
       7. The method of  claim 1 , where the calibration image appears to be stationary relative to an external environment. 
     
     
       8. The method of  claim 1 , where the calibration image is projected to a stationary location on the user's retina. 
     
     
       9. The method of  claim 1 , where the motion of the user's eye is sensed within 10 ms of projection of the calibration image onto the user's retina. 
     
     
       10. The method of  claim 1 , where the motion of the user's eye falls within a frequency band of 0 to 50 Hz. 
     
     
       11. The method of  claim 1 , where calibrating the alignment of the image source to the user's gaze comprises aligning the image source with a center of the user's foveal gaze. 
     
     
       12. The method of  claim 1 , where the calibration image focuses the user's gaze to a center of the calibration image. 
     
     
       13. A method for calibrating an alignment of an eye-mounted display to a user's gaze, the eye-mounted display comprising an image source, the method implemented on a system and comprising:
 providing a visual stimulus to the user comprising sequentially projecting a calibration image from the image source to different locations on the user's retina; 
 sensing one or more motions of the user's eye in reaction to each of the projected calibration images; and 
 calibrating the alignment of the image source to the user's gaze is based on the sensed motions. 
 
     
     
       14. The method of  claim 1 , where calibrating the alignment of the image source to the user's gaze comprises determining the location of a visual center for the image source. 
     
     
       15. The method of  claim 1 , where the method is performed automatically each time the user mounts the eye-mounted display on the user's eye. 
     
     
       16. The method of  claim 1 , where the method is performed in response to the user's request for calibration. 
     
     
       17. The method of  claim 1 , where the method is performed in response to the system automatically determining that the eye-mounted display requires calibration. 
     
     
       18. The method of  claim 1 , further comprising:
 prompting the user to direct the user's gaze to the calibration image. 
 
     
     
       19. The method of  claim 1 , where projecting the calibration image onto the user's retina causes an automatic reaction of the user to direct the user's gaze to the calibration image. 
     
     
       20. The method of  claim 1 , where the sensed motion is motion of the user's eye until the user's gaze has stabilized on the calibration image. 
     
     
       21. The method of  claim 20 , where calibrating the alignment of the image source to the user's gaze comprises determining a location on the image source from which the calibration image is projected when the user's gaze has stabilized on the calibration image. 
     
     
       22. The method of  claim 20 , where calibrating the alignment of the image source to the user's gaze comprises determining an offset between (a) a location on the image source from which the calibration image was initially projected, and (b) a location on the image source from which the calibration image is projected when the user's gaze has stabilized on the calibration image. 
     
     
       23. The method of  claim 20 , further comprising:
 determining that the user's gaze has stabilized based on whether the sensed motion has fallen below a threshold. 
 
     
     
       24. The method of  claim 20 , further comprising:
 determining that the user's gaze has stabilized based on one of a verbal indication from the user, a non-verbal indication from the user, and an eye gesture from the user. 
 
     
     
       25. The method of  claim 1 , further comprising:
 projecting subsequent images from the image source onto the user's retina using the calibrated alignment of the image source to the user's gaze. 
 
     
     
       26. An electronic contact lens, comprising:
 a display comprising one or more projectors configured to project images onto a user's retina; 
 a power source configured to provide power to components of the electronic contact lens; 
 a motion detection system configured to detect motion of the user's eye; and 
 a controller configured to calibrate an alignment of the display to the user's gaze by:
 providing a visual stimulus to the user by causing the display to project a calibration image onto the user's retina; and 
 responsive to the motion detection system detecting a motion of the user's eye, calibrating an alignment of the display to the user's gaze based on the detected motion by:
 comparing the detected motion to a threshold; and 
 based on the comparison:
 maintaining a location of a visual center of an image source of the display when the sensed motion is below a threshold, wherein the visual center is a location on the image source estimated to project to a center of the user's fovea; and 
 adjusting the location of the visual center of the image source when the sensed motion is greater than the threshold.